Port Bonython oil spill

The Port Bonython oil spill occurred on 30 August 1992, when the fuel tank of the tanker Era was pierced by the bow of the tugboat Turmoil during berthing operations in upper Spencer Gulf, South Australia. Wind and swell were high and 296 tonnes of bunker fuel were released into Spencer Gulf. The incident resulted in 500 oiled birds and damage to 15 km of mangrove and seagrass habitat south-west of Port Pirie.

The spill occurred at 10.52am, as the Era was berthing at the Port Bonython wharf in rough seas. The vessel had arrived to load oil for the Kwinana refinery. The Era was chartered by BP and the tugboat involved, Turmoil, was property of the Adelaide Steamship Company. Also present were the tugboat Taminga and the line-boat Wanilla. A lug on the Turmoil's bow pierced the hull of the tanker, leaving a 20 cm hole in the hull and rupturing her fuel tank. The 94,287 deadweight tonne vessel was listed 5 degrees to slow the flow of heavy bunker oil, and the leak was eventually stopped at 2.12pm. A total of 296 tonnes of heavy fuel oil had escaped into the sea.

The slick was described in the official report as "a moderate sheen with streaks of heavy dark oil moving round the stern of the vessel." Tug boats were driven through the slick in an attempt to break it up, and the spraying of chemical dispersant commenced soon after the spill occurred. 400 litres of Corexit 7764 and 4200 litres of Corexit 9527 were supplied by Santos.

The absence of an appropriate crane at the jetty made loading Turmoil with dispersant at Port Bonython impossible. Instead, the tugboat proceeded to Whyalla to load, while the dispersant was transported there by road. The Santos-owned Shark Cat Tregalana loaded in Santos' boat harbor. The other vessels present were unable to assist due to the Wanilla requiring towing by the Taminga. A line had fouled its propeller during the berthing of the Era.

Three different chemical dispersants were used: Corexit 7764, Corexit 9527 and Ardrox 6120. Strong north-westerly winds of up to 25 knots combined with tide and current initially transported the oil slick eastwards, towards Port Germein. The high winds prevented the early use of containment booms.

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